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(No Model.)

T. A. EDISON & J. F. OT'I'. OUT-OUT FOB. INOANDESOENT LAMPS.

No. 466,400. Patented Jan. 5, 1892.

UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF LLEXVELLYN PARK, AND JOHN F. OTT, OF NElVARK, NEW JERSEY, ASSIGNORS TO THE EDISON ELECTRIC LIGHT COMPANY, OF NEW YORK, N. Y.

CUT-OUT FOR INCANDESCENT LAMPS.

SPECIFICATION forming part of Letters Patent No. 466,400, dated January 5, 1892. Application filed October 27, 1886. Serial No. 217,314. (No modeL To all whom it may concern: small holes f f, are bent out upon the flat re- Be it known that we, THOMAS A. EDISON, cessed portion 1), so that the insulating-piece of Llewellyn Park, and JOHN F. OTT, of N ewis held upon the wires, and pass together ark, in the county of Essex and State of New through the aperture cl. Fixed within the re- 5 Jersey, have jointly invented a certain new cessed part b are two small bent-wire staples and useful Improvement in Incandescent g g, through each of which a wire a passes, Electric Lamps, (Case No. 681,) of which the so that such wires are respectively in electrifollowing is a specification. cal contact with the staples. Bent around a Our invention relates to incandescent elecscrew or pin h and held under the head there- 10 tric lamps designed to be used in series with of is a spring-wire r' i, the part 1' of which one another with currents of high electrorests in close contact with the staple g, while motive force. In the use of lamps in this way the part c" is held midway between the two diiiiculty arises from the breaking of the carstaples. The wire t" is thus held bya piece of bon filaments, because when the filament of thread or similar inflammable material is.

I 5 a lamp breaks either the circuit is thereby in- This thread is in the form of a loop knotted terrupted and all the other lamps in the searound the staple g passing around the staple ries are at once extinguished or an are forms g, and knotted again around spring-wire 2'. across the filament, which continues down the The thread 7c is coated or impregnated with a leading-in wires and into the stem of the lamp, material of high resistance or low electrical 20 and if itis not stopped or broken will penetrate conductivity. \Ve prefer to employ a mixture down into the socket and destroy the same, of powdered lamp-black with shellac, muciand ultimately also destroy, of course, the conlage, or other adhesive material. Such a detinulty of the circuit. gree of conductivity is thereby given to the The object of our invention is to provide thread that in the ordinary operation of the 2 5 within the lamp a simple and convenient cutlamp practically no currentwill pass across the out arrangement whereby both these difficul- .thread from staple g to g, or, in other words, ties will be obviated; and our invention conacross the wires a a, but on the cessation of sists in the novel devices and combinations current through the lamp in consequence of of devices employed by us in accomplishing the breaking of the circuit within the lamp 30 this object, as hereinafter set forth and the increased difference of potential between claimed. the wires a a at this point will permit current Our invention is illustrated in theaccomto pass across. We prefer to employ the cotpanying drawings, in whichton thread used ordinarily in needle-work Figure 1 is aview in elevation of an incanand with its strands twisted rather loosely.

35 descent electric lamp embodying said inven- The mixture of lamp-black and adhesive mation; Fig. 2, a vertical section of the cut-out terial is preferably rubbed in with the findevice in the stem of the lamp, and Fig. 3 a gers. cross-section on the line a; a: of Fig. 2. The operation of the devices is as follows:

A is the inclosing globe of the lamp, and B hen the filament C breaks, it no are forms 4 o the inner stem, through which pass the leadacross the filament the cessation of current ing-in wires a a, sealed in the stem at b and through the lamp causes current to pass in attached within the globe to the carbon filathe conducting-thread It so much as to at ment C. once burn and destroy the thread, and this D is a piece of vulcanized fiber or other suitreleases the spring-wire i, which at once flies 45 able insulating material placed within the back against the staple g, thereby connect- 5 stem of the lamp. It has a recess 1), and the ing wires d atogether and completing a short heads formed at the ends of the piece by such circuit around the filament, so that the conrecess have-the upper one c an aperture 61 tinuity of the series circuit is maintained. and the lower one e two small holes f f If, however, when the filament breaks an are 50 through it. The wires to a pass through the forms acrossit from below the point of breakxoo age to the opposite terminal, (which is usually the case,) such are continues down the wires a a, through the heated glass at I), and into the stem; but as soon as it reaches the thread 70 the thread is at once burned and the spring t" is released and completes the circuit, as already explained. By this arrangement we avoid the necessity of placing the wires in soldering proximity, which has heretofore been done, and also do away with the use of electro-magnetic cut-outs for the lamps.

\Vhat we claim is- 1. In an incandescent electric lamp, the combination, with the leading-in wires between the external contacts of the lamp and their place of sealinginto the glass, of a spring adapted to bridge said wires and an inflamm able fastening device normally holding such spring out of bridging contact, substantially as set forth.

2. In an incandescent electric lamp, the combination, with the leading-in wires within the stem of the lamp, of a spring adapted to bridge said wires, and an inflammable fastening device normally holding said spring out of bridging contact, substantially as set forth.

3. The combination, with the wires leading to the carbon filament of an incandescent electric lamp, of a spring adapted to bridge said wires, and a fastening device normally holding said spring out of contact and also bridging said wires and being of such electrical conductivity that practically no current will pass through it during the normal operation of the lamp, but that when circuit within the lamp is broken sufficient current will pass to destroy it, substantially as set forth.

4. The combination, with the wires leading to the carbon filament of an incandescent electric lamp, of a spring adapted to bridge said wires, and a thread secured to said wires and spring so as to hold said spring normally out of contact, said thread being of such electrical conductivity that practically no current will pass through it during the normal operation of the lamp, but that when circuit within the lamp is broken sufficient current will pass to destroy it, substantially as set forth.

5. The combination, in an incandescent electric lamp, of the insulating-piece within its stem, the V-shaped spring carried thereby, one end of which is connected with one of said wires, and the thread secured to the other end of said spring and to said wires, so as to normally hold said spring out of contact with the other wire, said thread being of such elec trical conductivity that practically no current will pass through it during the normal operation of the lamp, but that when circuit through the lamp is broken sufficient current will pass to destroy it, substantially as set forth.

6. The combination, in an incandescent electric lamp, of the recessed insulating-piece within its stem, the wires passing through the heads of said piece, the staples in said recess through which said Wires pass, the V-shaped spring having one end in contact with one of said staples, and the thread having electrical conductivity substantially such as specified and secured to said staples and normally holding the other end of said spring out of contact with the other staple, substantially as set forth.

7. The combination, in an incandescent electric lamp, of the wires, the spring adapted to bridge said wires, and the thread normally holding said spring out of contact and also bridging said wires, said thread being coated or impregnated with a conducting material, substantially as set forth.

This specification signed and witnessed this 26th day of October, 1886.

THOS. A. EDISON. JOHN F. OT Vitnesses:

WM. PELZER, E. G. ROWLAND. 

